glycolic acid prodn. by hydrolysis of mono:chloro-acetic acid - in (superheated) aq. soln. avoids pollution and contamination with salt

摘要

Glycollic acid (I) prodn. from monochloroacetic acid (II) involves hydrolysis of (II) in aq. soln. at 100-170 degrees C at a (II): water wt. ratio of 1:0.4-9. This is followed by removal of the HCl formed and concn. to the required (I) content under reduced pressure by (a) adding water (vapour) at under 70 degrees C until the residual water content is 15-30 wt. % or (b) concentration to a residual water content of 0.3 wt. % at a temp. below 170 degrees C, without addn. of water, followed by hydrolysis of the estolide fraction formed to (I) with water. Finally, the aq. (I) obtd. is diluted or conc. to the required concn. or, if 100% (I) is required, this is allowed to crystallise from the soln. Pure, salt-free (I) can be produced easily, without the formation of by-prods. which cause environmental pollution or other drawbacks.